The present disclosure relates generally to a method of manufacturing a light diffusing component, and, more particularly, to a method of manufacturing a light guide for use in a transparent or translucent display.
A typical transmissive display may include a liquid crystal stack illuminated by a uniform backlight. The backlight, in a transmissive display, is a collection made of the light guide with embedded scattering centers, light management films such as an IDF (image directing film) and a D-BEF (brightness enhancing film), followed by a diffuser. The combined performances of these light management films help deliver a backlight assembly with uniform brightness all across its dimensions. Because the backlight is hidden behind a number of components, including cross polarizers, the architecture of transmissive backlights is more forgiving.
The main structure of any LCD (liquid crystal display) system is the light guide that illuminates the many LCD cells. The most common and current implementation uses side-located LED light sources injecting light into the light guide. The light guide is itself embedded with scattering centers at the bottom surface. These scattering centers whether concave or convex are responsible for scattering and redirecting the light propagating through the light guide. If the scattering centers or dots are placed periodically along the light guide, the light extraction pattern follows an exponential decay, where most of the power is extracted at the beginning and gradually falls off as less and less power remains available in the light guide. To maintain uniform brightness across the whole light guide, the scattering center distribution must be such that less extraction scattering centers are available where the power is high (near the LEDs) and more extraction scattering centers are made available where the power is low. In such an implementation, the size of the scattering centers often remains constant and well-defined (typically hundreds of microns to a millimeter in size), while the distance between scattering centers decreases from around 300-μm near the LEDs to around 30-μm at the opposite end of a one-dimensional gradient.
A recent trend in displays is toward transparent and translucent displays. Potential uses for transparent or translucent displays include hospital walls, building windows, digital signage, window advertisement, and heads-up displays. Transparent displays may stimulate the concept of display on demand, where the display will only be there when you want it.
Different from a transmissive display, in a transparent or translucent display, the only components that may be present are the translucent LCD stack and the light guide. In a transparent or translucent display, there are no more diffusers, light management films, or back reflector. Such displays may require light scattering centers that are extremely small, so as to be invisible. The light scattering centers may also need to be randomized to minimize any interference (Moire) with the LCD stack.
Similar to a transmissive display, in order to compensate for the natural exponential decay observed as light propagates through the light-guide, a gradient may be needed in the scattering center distribution of a transparent or translucent display to allow uniform light extraction.
The present disclosure provides a method of manufacturing a light diffusing component, or light guide, for use in a transparent or translucent display.